This invention relates to thermoplastic polymers which are useful in molding centers for golf balls. More particularly, it relates to the use of thermoplastic polymers composed of block radial polymers of the dienearyl substituted olefin butadiene-styrene type which contains a major portion of a filler material as well as an extender to form a golf ball center having high rebound characteristics as well as offering versatility in meeting manufacturing specifications.
Currently golf balls are produced in the following forms:
1. A one component solid construction composed of a homogeneous mass consisting of polybutadiene, monomers, fillers, antioxidants, curing agents, etc.
2. A two component golf ball comprising a cover composed of natural rubber (Balata) or plastic (Surlyn) including urethanes; and a core composed of a solid homogeneous mass similar to Item #1.
3. A three component golf ball composed of a cover composed of Balata rubber, plastic (Surlyn) or similar material; a winding composed of natural and/or synthetic rubber thread; and a core made from natural or synthetic polymers.
4. A four component golf ball having a cover as described in Items 2 and 3; a winding as described in Item 3; a core wall made from natural and/or synthetic rubber; and a liquid center composed of glycerin; polyethylene glycol, salt solutions, etc.
The golf ball center of the type concerned with in this invention is the Center or Core in Item 3.
Block copolymers of butadiene-styrene and styrene-butadiene-styrene type are described in U.S. Pat. No. 3,534,965 to produce a solid golf ball. The block copolymers are blended and cured to result in the solid golf ball. Styrene-butadiene copolymers are also vulcanized in a blend with a polytetrahydrofuran to form a molded golf ball in U.S. Pat. No. 3,373,123. In U.S. Pat. Nos. 4,048,254 and 4,048,255 blends of uncured radial block copolymers are described for use with a third polymeric material for use in making thermoplastic materials for pharmaceutical purposes. The prior art nowhere describes an uncured, butadiene-styrene radial block copolymer having a specific butadiene and styrene content in combination with a major portion of a filler material for use in the manufacture of a solid golf ball center. Neither does the prior art indicate that an uncured butadiene-styrene radial block copolymer can be employed in formulations for composing golf ball centers wherein the use of fillers and extenders can be freely incorporated to obtain centers having high rebound and various durometers.
It is an advantage of the present invention to provide a solid golf ball center composed of an uncured butadiene-styrene radial block copolymer. Other advantages are a solid golf ball center containing a major portion of filler material as well as extenders so as to permit versatility in achieving desired properties for a golf ball; a solid golf ball center which can be molded by various molding techniques including injection molding so as to afford rapid production as well as size and weight control; a solid golf ball composition which eliminates the need for curing and permits the reuse of trim and runner system material.